"Who wants to earn some money?"
It was just a simple question, but it was enough to convince María (not her real name) to enter into what seemed like a simple deal.
A young woman offered the 46-year-old Costa Rican woman 110 colones ($200; £140) to get married to a Chinese man so that he could get residency in the Central American country.
At the time, María lived in one of the poorest areas of the Costa Rican capital, San José, and was desperate for help to feed her family.
"We did not have anything to eat," María says of her decision to say yes.
'They look for prey'
María's neighbourhood is not known for its safety. "Around here, the less you know, the longer you live," a resident warns.
What happened to María is not uncommon here. A lawyer or middleman arrives looking for the most desperate and convinces them to marry a foreigner they have not even met.
"They look for prey… People here are in dire need. However little they offer, people accept without giving it a second thought," another resident explains.
María got married without even leaving her neighbourhood. She just got into a car, where she signed a marriage certificate and received her 110 colones in exchange on the understanding that she would get divorced as soon as possible.
She says that was all the explanation she was given. "They just showed me a photo of the Chinese guy and told me: 'Miss María, you are getting married to this Chinese man'," she explains.
In María's case, the middleman kept up his side of the bargain and came back with the divorce papers some time later.
A few years later, she married another Chinese citizen for money, as did some of her daughters, and her partner, too.
The government says María's case is part of a serious problem, the extent of which is hard to measure.
Deputy state prosecutor Guillermo Fernández says his office is currently investigating more than 1,000 cases of suspected sham marriages.
Mr Fernández says he fears that this number is "just the tip of the iceberg".
The director of Costa Rica's office for migration, Gisela Yockchen, speaks of a "black market" for sham marriages run by Costa Rican criminal networks.
She says that these "mafias" operate in different ways, with some going as far as stealing people's identities to marry them off to foreigners looking for legal residency or even nationality through marriage.
The first the victims of this particular scam know about it is when they find out to their shock that their civil status has changed from "single" to "married" without their knowledge or consent.
In other cases, those who entered knowingly into a sham marriage in exchange for money find that the divorce promised to them never comes through, leaving them married to a partner they have never met and do not even know how to track down.
Ms Yockchen says that the foreigners are often also unwitting victims.
An official document seen by the BBC suggests that a Chinese national – who did not speak any Spanish – signed a document that he thought was an application for residency when it was in fact a marriage certificate.
Ms Yockchen says that a stricter immigration law introduced in 2010 has gone some way towards tackling the problem. Under that law, notaries and others involved in arranging fake marriages can be sentenced to up to five years in prison.
Since then, permanent residency has no longer automatically been granted to foreigners just for being married to a Costa Rican citizen.
Foreign citizens can still apply for residency permits after marrying a Costa Rican partner and having had their marriage certificate registered at the Civil Registry, but the permit they are given is restricted to a year.
It can be renewed annually if the couple provides evidence that they are cohabiting as husband and wife. After three years, the foreign partner can apply for permanent residency.
'Gateway to the US'
Most of the Chinese who have migrated to Costa Rica come from the southern province of Guangdong, Uned researcher Alonso Rodríguez says.
Many choose Costa Rica because of its immigration-friendly policies and its reputation for being a relatively safe country.
There is also a long history of immigration to Costa Rica, with the first Chinese arriving in 1855 to work as field hands.
But the final destination of today's Chinese migrants is not necessarily Costa Rica. "For many, it is a gateway to the US," Mr Rodríguez explains.
If they stay in Costa Rica, they often open and run small businesses. "They adapt very well to the way of life here," he says.
Li Zhong is one of those who has settled in Costa Rica. She runs a convenience store in San José.
Asked about how she came to Costa Rica she says that she "bought her way into Panama".
After having "problems" with the authorities in Panama, she moved to Costa Rica. Her son has since joined her and has opened his own store.
When the subject of sham marriages comes up, Li is evasive but confirms that she knows of many Chinese-Costa Ricans couples.
She jokes that marriages between Chinese men and Costa Rican women have proven easier than marriages between Costa Rica men and Chinese women.
"Ticos mean trouble, with ticas it's better," she says referring to the colloquial term used for Costa Ricans.
Like many Chinese, Li already has a Costa Rican in her family. Just that in her case, it is not a husband she married to be able to get residency but her grandson, who was born in the Central American country.
Watching him run around the shop, Li says proudly: "He is a tico!"